The present invention generally relates to handling and stacking equipment for sheet-type articles and materials. The invention particularly relates to sheet handling and stacking machines adapted to stack sheets of tin plate and other metallic sheets that are relatively heavy and susceptible to damage during a stacking operation.
“Tin plate” is a term that is commonly used to refer to metal sheet materials of the type used to produce the outer cylinders of cans, for example, food, beverage, and aerosol cans. Prior to being formed to produce a can, tin plate sheets are typically processed to have a printed surface so that each individual sheet provides the printed information desired or required for the final can product. The sheets are individually printed and stacked prior to being delivered to equipment that forms and welds the sheets and then assembles the resulting cylinder with one or more ends, for example, to produce a three-piece can.
A particular stacking machine known in industry has been referred to as a Dexter Stacker, which had been manufactured by the Dexter Folder Company and/or its successor, Miehle-Goss-Dexter, Inc. A particular machine of this type is capable of stacking sheets at high rates onto a pallet. However, a problem encountered with such machines is that tin plate and other relatively heavy sheets tend to “dive” as they fall onto the pallet, causing the sheet to scratch the upper surface of the preceding sheet in the stack. In the case of printed tin plate used to produce cans, damage can occur to the printed surface. Because printed tin plate sheets must ordinarily undergo stacking prior to deliver to the forming equipment, there is a need to be able to stack the sheets without scratching their printed surfaces.